Averroism was a philosophical trend among scholastics in the late 1200s based on Averroës interpretations of Aristotle.

The main ideas of averroism (founded in Averroës commentaries to Aristoteles) was:

  • that the world was eternal
  • the soul was divided in two parts, one individual part and one divine part
  • that the individual soul was not eternal and
  • that all humans at the basic level shared one and the same divine soul, also known as monopsychism
  • the resurrection of the dead is not possible (Boëthius)

This standpoint resulted in averroism being banned twice, first in 1270 and then again in 1277, this time by the bishop Etienne Tempier of the Catholic church. Tempier specified 219 different unacceptable averroist theses. To resolve the problem, Sigerus of Brabant tried to claim that there existed a "double truth": one factual or "hard truth" which is reached by science and philosophy, and one "religious truth" reach through religion. This idea had not originated in Averroës.

The later philosophical concept of averroism was the idea that the philosophical and religious worlds are separate entities. However, upon scrutinizing the 219 theses condemned by Tempier, it was obvious that not many of them originated in Averroës, so for a while other terms were commonly used to refer to the actual philosophical movement started by Sigerus and Boëthius: Radical Aristotelianism or Heterodox Aristotelianism are other words used for this movement, but nowadays most call it averroism anyway.

Thomas Aquinas specifically attacked the doctrine of monopsychism in his book De unitate intellectus contra Averroistas. In this context, the word averroism is used correctly.

See Also